Electrophoretic Display Refresh Control for Image Disturbance
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Solution Overview
Problem
Electrophoretic display devices face issues with image disturbance due to partial rewriting, leading to afterimage accumulation and user inconvenience, as existing refresh methods either delay necessary resets or cause frequent full-screen black or white displays.
Innovation Solution
A display device with a calculation unit that tracks the number of pixels changed during partial rewriting and a refresh control unit that executes a refresh operation when the accumulated number of update pixels exceeds a defined value, allowing for targeted and timely refresh operations to prevent image disturbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refresh operation is executed every predetermined period to prevent image disturbance, then image quality is improved, but user convenience deteriorates due to frequent full-screen black or white displays
Solution Approach 1:
The patent applies local quality by performing refresh operations selectively on specific pixel regions rather than uniformly across the entire display. The controller divides the display into multiple regions and executes refresh operations only on regions where afterimage accumulation exceeds a threshold, thereby maintaining image quality while avoiding unnecessary full-screen resets that disrupt user experience.
Solution Approach 2:
The patent implements partial action by executing refresh operations on only the necessary portions of the display. Instead of performing complete full-screen refresh operations at fixed intervals, the system performs partial refresh operations on specific pixel regions where needed, reducing the frequency of visually disruptive full-screen resets while still preventing image disturbance.
2Reliability
If reset-driving is performed on pixels in partial rewriting regions, then image disturbance is prevented, but contrast difference occurs between reset regions and other regions
Solution Approach 1:
The patent applies partial action by performing reset-driving only on specific pixel regions where afterimage accumulation is detected, rather than uniformly across the entire display. This selective approach prevents image disturbance in affected areas while minimizing contrast differences, as non-reset regions maintain their original display states and are not subjected to uniform white or black cancellation displays.
3Productivity
If partial rewriting is performed repeatedly, then writing efficiency is improved, but afterimages accumulate causing image disturbance
Solution Approach 1:
The patent implements feedback by continuously monitoring the number of rewriting operations on each pixel region and comparing it against a threshold value. When the rewrite count exceeds the threshold, the system automatically triggers a refresh operation to clear accumulated afterimages. This closed-loop feedback mechanism allows efficient partial rewriting to continue while preventing image disturbance through timely, targeted refresh operations.
Solution Approach 2:
The patent applies periodic action by executing refresh operations at intervals determined by rewrite counts rather than fixed time periods. The system performs refresh operations periodically based on the accumulation of rewriting operations, clearing afterimages before they cause visible disturbance while maintaining high writing efficiency during intervals between refreshes.
Data Source
AI summary
A display device including a display unit having a plurality of pixels includes a calculation unit which accumulates the number of pixels of which display state is changed among the plurality of pixels so as to calculate the accumulated number of update pixels when a part of an image displayed on the display unit is changed, and a refresh control unit which executes a refresh operation of the display unit when the calculated accumulated number of update pixels becomes equal to or more than a defined value.